Regan started playing rugby underage at Birr RFC in County Offaly and was part of the Leinster under-age set up.
Regan made his senior competitive debut for Ulster in their 54–42 defeat against Leinster in the 2018–19 Pro14 on 20 December 2019, coming on as a replacement in this match.
Regan moved to New Zealand where he joined the Dunedin Sharks and was subsequently signed by Otago.
[2] In February 2021 Regan was called into the Highlanders squad as injury cover for some pre-season games.
Regan made his Super Rugby debut for the Highlanders on 26 February in a 13–26 defeat to the Crusaders.